Recommended format for conversion to image sequences (particularly from DVD

[richardjc]

Hi,

I'd like some info (general principles) regarding converting video to image sequences, particularly regarding quality. I suspect TGA is an all round ideal format? What about when converting from DVD (vob)? Is TGA overkill? Are JPGs adequate to the task? And Im correct in thinking PNGs have the same quality to JPGs (just the additional alpha channel)?

Actually, whilst Im here... Does anyone know if Premiere or vdub offer an option to encode into image sequences only designated frames, e.g. every second frame (for rotoscoping use)? Will adjusting the output framerate do the trick?

Thanks kindly!

Richard.

[filmboss80]

I've done it many times with Premiere, saving the sequence as a series of .bmp files that could be rotoscoped (or altered in other ways) using Photoshop. The series of .bmp files can thereafter be reimported into Premiere as a video clip and dropped back into the timeline. Consult your user's manual or Premiere's help file. If you want to remove frames, you simply pull out the individual .bmp files you do not want to use. (Each video frame produces its own .bmp image.)

[poisondeathray]

.png has lossless compression and can preserve alpha channel. .jpg is lossy and should not be used. .tga and .bmp are lossless but not compressed.

vdub can export a frame range. avisynth can also and has the most control, but you need some basic scripting knowledge beforehand

[jagabo]

.jpg is lossy and should not be used

It might be "adequate" for the OP's purpose.

[richardjc]

Thanks kindly for all the advice.

Cheers,
Richard

[themaster1]

Is TGA overkill?

yes, bmp is just fine

Are JPGs adequate to the task?

I'm affraid they're not

And Im correct in thinking PNGs have the same quality to JPGs (just the additional alpha channel)?

Avoid jpeg & png by any means necessary, especially jpeg, png support the alpha chan yep

Does anyone know if Premiere or vdub offer an option to encode into image sequences only designated frames, e.g. every second frame (for rotoscoping use)? Will adjusting the output framerate do the trick?

(on vdub) I don't think so but you could select a specific segment and add it to the job list and redo this operation at will then process the job(s)

[jagabo]

24 and 32 bit TGA, and BMP are more-or-less equivalent. Fewer programs can handle TGA, some can't handle RLE encoded (losslessly compressed) TGA. PNG output from VirtualDub is losslessly compressed.

In VirtualDub You can use the Video -> Frame Rate option to decimate the image sequence output. You can use the mark-in and mark-out tools to break a video into segments.